What is the product?

[tex]\[
\left(x^4\right)\left(3x^3 - 2\right)\left(4x^2 + 5x\right)
\][/tex]

A. \( 12x^9 + 15x^8 - 8x^6 - 10x^5 \)

B. \( 12x^{24} + 15x^{12} - 8x^8 - 10x^4 \)

C. \( 12x^9 - 10x^5 \)

D. [tex]\( 12x^{24} - 10x^4 \)[/tex]



Answer :

To determine the product of the expressions \((x^4)\), \((3x^3 - 2)\), and \((4 x^2 + 5 x)\), we will follow these steps:

1. Multiply the first two expressions:

Consider the first two expressions, \(x^4\) and \(3x^3 - 2\):

[tex]\[ x^4 \cdot (3x^3 - 2) = x^4 \cdot 3x^3 - x^4 \cdot 2 = 3x^7 - 2x^4 \][/tex]

2. Multiply the result with the third expression:

Now, multiply the expression obtained in step 1, which is \(3x^7 - 2x^4\), by \(4x^2 + 5x\):

Consider the product \( (3x^7 - 2x^4)(4x^2 + 5x) \). We will use the distributive property:

[tex]\[ \begin{align*} (3x^7 - 2x^4)(4x^2 + 5x) &= 3x^7 \cdot 4x^2 + 3x^7 \cdot 5x - 2x^4 \cdot 4x^2 - 2x^4 \cdot 5x \\ &= 3x^7 \cdot 4x^2 + 3x^7 \cdot 5x - 2x^4 \cdot 4x^2 - 2x^4 \cdot 5x \\ &= 12x^9 + 15x^8 - 8x^6 - 10x^5 \end{align*} \][/tex]

3. Compare the result with the given options:

The resulting polynomial from the multiplication is:

[tex]\[ 12 x^9 + 15 x^8 - 8 x^6 - 10 x^5 \][/tex]

4. Identify the correct option:

- The first choice is \(12 x^9 + 15 x^8 - 8 x^6 - 10 x^5\), which exactly matches our computed result.
- The other choices are: \(12 x^{24} + 15 x^{12} - 8 x^8 - 10 x^4\), \(12 x^9 - 10 x^5\), and \(12 x^{24} - 10 x^4\). None of these match our result.

Therefore, the correct answer to the question is:
[tex]\[ 12 x^9 + 15 x^8 - 8 x^6 - 10 x^5 \][/tex]

Hence, the correct option is the first one.